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<Font Color="blue"> Classe cristalline arithmétique </Font> (''Fr.''). <Font Color="red"> Arithmetische Kristallklasse </Font>(''Ge''). <Font Color="green">Clase cristallina aritmética</Font>(''Sp''). <Font color="black"> Classe cristallina aritmetica </Font>(''It'')
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<font color="blue">Classe cristalline arithmétique</font> (''Fr''). <font color="red">Arithmetische Kristallklasse</font> (''Ge''). <font color="black">Classe cristallina aritmetica</font> (''It''). <font color="purple">代数的結晶類</font> (''Ja''). <font color="green">Clase cristalina aritmética</font> (''Sp'').
  
  
 
== Definition ==
 
== Definition ==
  
The '''arithmetic crystal classes''' are obtained in an elementary fashion by combining the [[geometric crystal classes]] and the corrresponding types of Bravais lattices. For instance, in the monoclinic system, there are three geometric crystal classes, 2, ''m'' and 2/''m'', and two types of Bravais lattices, ''P'' and ''C''. There are therefore six monoclinic arithmetic crystal classes. Their symbols are obtained by juxtaposing the symbol of the geometric class and that of the Bravais lattice, in that order: 2''P'', 2''C'', ''mP'', ''mC'', 2/''mP'', 2/''mC'' (note that in the space group symbol the order is inversed: ''P''2, ''C''2, etc...). In some cases, the centring vectors of the Bravais lattice and some symmetry elements of the crystal class may or may not be parallel; for instance, in the geometric crystal class ''mm'' with the Bravais lattice ''C'', the centring vector and the two-fold axis may be perpendicular or coplanar, giving rise to two different arithmetic crystal classes, ''mm''2''C'' and 2''mmC'' (or ''mm''2''A'', since it is usual to orient the two-fold axis parallel to ''c''), respectively. There are 13 two-dimensional arithmetic crystal classes and 73 three-dimensional arithmetic crystal classes that are listed in the attached [[Arithmetic crystal class| table]]. They do not contain glide or screw elements and are therefore in one to one correspondence with the [[symmorphic space groups]].
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The '''arithmetic crystal classes''' are obtained in an elementary fashion by combining the [[geometric crystal class]]es and the corresponding types of Bravais lattices. For instance, in the monoclinic system, there are three geometric crystal classes, 2, ''m'' and 2/''m'', and two types of Bravais lattices, ''P'' and ''C''. There are therefore six monoclinic arithmetic crystal classes. Their symbols are obtained by juxtaposing the symbol of the geometric class and that of the Bravais lattice, in that order: 2''P'', 2''C'', ''mP'', ''mC'', 2/''mP'', 2/''mC'' (note that in the space group symbol the order is inversed: ''P''2, ''C''2, ''etc.''). In some cases, the centring vectors of the Bravais lattice and some symmetry elements of the crystal class may or may not be parallel; for instance, in the geometric crystal class ''mm'' with the Bravais lattice ''C'', the centring vector and the two-fold axis may be perpendicular or coplanar, giving rise to two different arithmetic crystal classes, ''mm''2''C'' and 2''mmC'' (or ''mm''2''A'', since it is usual to orient the two-fold axis parallel to ''c''), respectively. There are 13 two-dimensional arithmetic crystal classes and 73 three-dimensional arithmetic crystal classes that are listed in the attached [[Arithmetic crystal class| table]]. Space groups belonging to the same geometric crystal class and with the same type of Bravais lattice belong to the same arithmetic crystal class; these are therefore in one to one correspondence with the [[symmorphic space groups]].
  
The group-theoretical definition of the arithmetic crystal classes is given in Section 8.2.3 of ''International Tables of Crystallography, Volume A''.
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The group-theoretical definition of the arithmetic crystal classes is given in Chapter 1.3.4.4.1 of ''International Tables for Crystallography, Volume A'', 6th edition.
  
== List of arithmetic crystall classes in three dimensions ==
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== List of arithmetic crystal classes in three dimensions ==
  
 
<table border cellspacing=0 cellpadding=5 align=center>
 
<table border cellspacing=0 cellpadding=5 align=center>
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</tr>
 
</tr>
 
<tr align=center>
 
<tr align=center>
     <td rowspan=6><math> mm </math></td>
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     <td rowspan=6><math> mm2 </math></td>
 
   <td> 13 </td>
 
   <td> 13 </td>
 
   <td><math> mm2P </math></td>
 
   <td><math> mm2P </math></td>
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   </tr>
 
   </tr>
 
<tr align=center>
 
<tr align=center>
   <td rowspan=4><math> {\bar 4}m </math></td>
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   <td rowspan=4><math> {\bar 4}m2 </math></td>
 
   <td> 32 </td>
 
   <td> 32 </td>
 
   <td><math> {\bar 4}2mP </math></td>
 
   <td><math> {\bar 4}2mP </math></td>
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   </tr>
 
   </tr>
 
<tr align=center>
 
<tr align=center>
   <td rowspan=2><math> {\bar 6}m </math></td>
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   <td rowspan=2><math> {\bar 6}m2 </math></td>
 
   <td> 56 </td>
 
   <td> 56 </td>
 
   <td><math> {\bar 6}2mP </math></td>
 
   <td><math> {\bar 6}2mP </math></td>
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   <td><math> 6/mmm </math></td>
 
   <td><math> 6/mmm </math></td>
 
   <td> 58 </td>
 
   <td> 58 </td>
   <td><math> 6/mmm </math></td>
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   <td><math> 6/mmmP </math></td>
 
   </tr>
 
   </tr>
  
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== See also ==
 
== See also ==
 
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*[[Geometric crystal class]]
Section 8.2.3 of ''International Tables of Crystallography, Volume A''<br>
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*Chapter 1.3.4.4.1 of ''International Tables for Crystallography, Volume A'', 6th edition<br>
Sections 1.3.4 and 1.5.3 of ''International Tables of Crystallography, Volume B''<br>
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*Chapters 1.3.4 and 1.5.3 of ''International Tables for Crystallography, Volume B''<br>
Section 1.4 of ''International Tables of Crystallography, Volume C''<br>
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*Chapter 1.4 of ''International Tables for Crystallography, Volume C''<br>
 
 
  
 
[[Category:Fundamental crystallography]]
 
[[Category:Fundamental crystallography]]

Latest revision as of 18:04, 8 November 2017

Classe cristalline arithmétique (Fr). Arithmetische Kristallklasse (Ge). Classe cristallina aritmetica (It). 代数的結晶類 (Ja). Clase cristalina aritmética (Sp).


Definition

The arithmetic crystal classes are obtained in an elementary fashion by combining the geometric crystal classes and the corresponding types of Bravais lattices. For instance, in the monoclinic system, there are three geometric crystal classes, 2, m and 2/m, and two types of Bravais lattices, P and C. There are therefore six monoclinic arithmetic crystal classes. Their symbols are obtained by juxtaposing the symbol of the geometric class and that of the Bravais lattice, in that order: 2P, 2C, mP, mC, 2/mP, 2/mC (note that in the space group symbol the order is inversed: P2, C2, etc.). In some cases, the centring vectors of the Bravais lattice and some symmetry elements of the crystal class may or may not be parallel; for instance, in the geometric crystal class mm with the Bravais lattice C, the centring vector and the two-fold axis may be perpendicular or coplanar, giving rise to two different arithmetic crystal classes, mm2C and 2mmC (or mm2A, since it is usual to orient the two-fold axis parallel to c), respectively. There are 13 two-dimensional arithmetic crystal classes and 73 three-dimensional arithmetic crystal classes that are listed in the attached table. Space groups belonging to the same geometric crystal class and with the same type of Bravais lattice belong to the same arithmetic crystal class; these are therefore in one to one correspondence with the symmorphic space groups.

The group-theoretical definition of the arithmetic crystal classes is given in Chapter 1.3.4.4.1 of International Tables for Crystallography, Volume A, 6th edition.

List of arithmetic crystal classes in three dimensions

Three-dimensional arithmetic crystal classes.
Crystal systems Crystal class
Geometric Arithmetic
Number Symbol
Triclinic [math] 1 [/math] 1 [math] 1P [/math]
[math] {\bar 1} [/math] 2 [math] {\bar 1}P [/math]
Monoclinic [math] 2 [/math] 3 [math] 2P [/math]
[math] m [/math] 4 [math] 2C [/math]
5 [math] mP [/math]
[math] 2/m [/math] 6 [math] mC [/math]
7 [math] 2/m P [/math]
8 [math] 2/mC [/math]
Orthorhombic [math] 222 [/math] 9 [math] 222P [/math]
10 [math] 222C [/math]
11 [math] 222F [/math]
12 [math] 222I [/math]
[math] mm2 [/math] 13 [math] mm2P [/math]
14 [math] mm2C [/math]
15 [math] 2mmC [/math]
[math] (mm2A) [/math]
16 [math] mm2F [/math]
17 [math] mm2I [/math]
[math] mmm [/math] 18 [math] mmmP [/math]
19 [math] mmmC [/math]
20 [math] mmmF [/math]
21 [math] mmmI [/math]
Tetragonal [math] 4 [/math] 22 [math] 4P [/math]
23 [math] 4I [/math]
[math] {\bar 4} [/math] 24 [math] {\bar 4}P [/math]
25 [math] {\bar 4}I [/math]
[math] 4/m [/math] 26 [math] 4/mP [/math]
27 [math] 4/mI [/math]
[math] 422 [/math] 28 [math] 422P [/math]
29 [math] 422I [/math]
[math] 4mm [/math] 30 [math] 4mmP [/math]
31 [math] 4mmI [/math]
[math] {\bar 4}m2 [/math] 32 [math] {\bar 4}2mP [/math]
33 [math] {\bar 4}m2P [/math]
34 [math] {\bar 4}m2I [/math]
35 [math] {\bar 4}2mI [/math]
[math] 4/mmm [/math] 36 [math] 4/mmmP [/math]
37 [math] 4/mmmI [/math]
Trigonal [math] 3 [/math] 38 [math] 3P [/math]
39 [math] 3R [/math]
[math] {\bar 3} [/math] 40 [math] {\bar 3}P [/math]
41 [math] {\bar 3}R [/math]
[math] 32 [/math] 42 [math] 312P [/math]
43 [math] 321P [/math]
44 [math] 32R [/math]
[math] 3m [/math] 45 [math] 3m1P [/math]
46 [math] 31mP [/math]
47 [math] 3mR [/math]
[math] {\bar 3}m [/math] 48 [math] {\bar 3}1mP [/math]
49 [math] {\bar 3}m1P [/math]
50 [math] {\bar 3}mR [/math]
Hexagonal [math] 6 [/math] 51 [math] 6P [/math]
[math] {\bar 6} [/math] 52 [math] {\bar 6}P [/math]
[math] 6/m [/math] 53 [math] 6/mP [/math]
[math] 622 [/math] 54 [math] 622P [/math]
[math] 6mm [/math] 55 [math] 6mmP [/math]
[math] {\bar 6}m2 [/math] 56 [math] {\bar 6}2mP [/math]
57 [math] {\bar 6}m2P [/math]
[math] 6/mmm [/math] 58 [math] 6/mmmP [/math]
Cubic [math] 23 [/math] 59 [math] 23P [/math]
60 [math] 23F [/math]
61 [math] 23I [/math]
[math] m{\bar 3} [/math] 62 [math] m{\bar 3}P [/math]
63 [math] m{\bar 3}F [/math]
64 [math] m{\bar 3}I [/math]
[math] 432 [/math] 65 [math] 432P [/math]
66 [math] 432F [/math]
67 [math] 432I [/math]
[math] {\bar 4}3m [/math] 68 [math] {\bar 4}3m P [/math]
69 [math] {\bar 4}3m F [/math]
70 [math] {\bar 4}3m I [/math]
[math] m{\bar 3}m [/math] 71 [math] m{\bar 3}mP [/math]
72 [math] m{\bar 3}mF [/math]
73 [math] m{\bar 3}mI [/math]

See also

  • Geometric crystal class
  • Chapter 1.3.4.4.1 of International Tables for Crystallography, Volume A, 6th edition
  • Chapters 1.3.4 and 1.5.3 of International Tables for Crystallography, Volume B
  • Chapter 1.4 of International Tables for Crystallography, Volume C